1. Field of Invention
The present invention relates to a Home Power Unit for Hybrid Electric Vehicles (xe2x80x9cHEVsxe2x80x9d) that acts as a general charger for the vehicle""s battery and as a generator to operate external electrical devices, such as power tools.
2. Discussion of the Prior Art
The need to reduce fossil fuel consumption and pollutants of automobiles and other vehicles powered by Internal Combustion Engines (xe2x80x9cICEsxe2x80x9d) is well known. Vehicles powered by electric motors have attempted to address these needs. However, electric vehicles have limited range and limited power coupled with the substantial time needed to recharge their batteries. An alternative solution is to combine both an ICE and electric traction motor into one vehicle. Such vehicles are typically called Hybrid Electric Vehicles (xe2x80x9cHEVsxe2x80x9d). See generally, U.S. Pat. No. 5,343,970 (Severinsky).
The HEV has been described in a variety of configurations. Many HEV patents disclose systems where an operator is required to select between electric and internal combustion operation. In other, the electric motor drives one set of wheels and the ICE drives a different set.
Other configurations have developed. A Series Hybrid Electric Vehicle (xe2x80x9cSHEVxe2x80x9d) is a vehicle with an engine (most typically an ICE) which powers a generator. The generator, in turn, provides electricity for a battery and motor coupled to the drive wheels of the vehicle. There is no mechanical connection between the engine and the drive wheels. A Parallel Hybrid Electrical Vehicle (xe2x80x9cPHEVxe2x80x9d) is a vehicle with an engine (most typically an ICE), battery, and electric motor combined to provide torque to power the wheels of the vehicle.
A Parallel/Series Hybrid Electric Vehicle (xe2x80x9cPSHEVxe2x80x9d) has characteristics of both a PHEV and a SHEV. The PSHEV is also known as a torque (or power) splitting powertrain configuration. Here, the torque output of the engine is given in part to the drive wheels and in part to an electrical generator. The electric generator powers a battery and motor that also provide torque output. In this configuration, torque output can come from either source or both simultaneously. In this configuration the vehicle braking system can even deliver torque to drive the generator to produce charge to the battery.
As the HEV continues to develop, new challenges are encountered and new uses are developed. One of the main challenges associated with all HEVs is insuring enough battery charge to start and operate the vehicle. All batteries lose charge as a result of use or lapse of time. Generally, the HEV battery is charged by an ICE Generator in the vehicle; however, during unusual conditions or emergencies, external battery charging may be necessary.
A potential use for the HEV is to utilize its battery and generator as a source of electrical power to operate electrical devices such as power tools. This type of vehicle use for auxiliary electrical power is well known for conventional ICE vehicles. Specifically, many patents have been issued utilizing the components of ICEs as a power source for electrical devices. For example, U.S. Pat. No. 3,824,404 (Leonard Ghere); U.S. Pat. No. 3,953,740 (Charles Seiter, Jr.); U.S. Pat. No. 4,074,145 (P. Laffoon, et al.); and U.S. Pat. No. 5,066,866 (William Hallidy), disclose various methods of utilizing a vehicle""s alternator to generate AC voltage to power electrical devices. However, these patents do not apply to HEVs because the HEV does not require an alternator. The HEV already has a ready source of electrical power within its battery and can generate additional power with an onboard generator. However, the HEV""s electrical power, needs to be converted for external use by electrical devices.
It is beneficial, economical, and efficient to have an apparatus, system and method that incorporates an HEV charging system with the ability to harness the vehicle""s electrical power system for auxiliary electrical applications.
The present provides a method, system, and apparatus for charging an HEV battery and utilizing the HEV as a generator to operate external electrical devices. The apparatus is called a Home Power Unit (xe2x80x9cHPUxe2x80x9d) and combines these two functions into one apparatus or system. This provides efficient and easy use of the invention.
The HPU, as a charger, provides the user with the ability to charge the HEV""s battery during emergency or unusual conditions. Generally, the battery is charged through the operation of an onboard generator in combination with the engine. If the onboard high voltage battery charge depletes completely, the engine would not be able to start. Therefore, it is necessary to have a way to charge a HEV battery. The present invention provides just such a means.
The HPU also operates as a generator allowing a user to draw upon the vehicle""s electrical power to run external electrical devices. The HPU draws power from the HEV""s generator and to some extent, its battery. The HPU converts this power to a useable form for external electrical devices such as power tools.
In both modes, the HPU functions as a conversion device to convert external AC electrical power sources to DC power for charging the REV battery (charger function) or convert on board DC electric power to AC electric power (generator function). In both modes the HPU is also capable of converting from one desired voltage to another (i.e., from low 110 to high 300 or reverse). In its simplest form, a HPU apparatus comprises a Transformer to convert electrical voltages, inverter means to convert DC to AC, rectifier means to convert AC to DC, a control unit, a connection means to the HEV and external electrical loads or sources, and a switching means to change operation between the charger and the generator functions. The apparatus typically connects to external loads or services through connection means with the Transformer. The HPU then connects to the HEV""s High Voltage DC Bus and system controllers, specifically, the Battery Electronic Control Unit. The switching devices for the HPU may comprise a momentary two position switch on the instrumental panel, a menu selection from an on-screen display mounted in the instrumental panel or a two position switch mounted on the HPU.
In an alternative embodiment, the HPU is incorporated directly into the components of the HEV. In this manner, redundant components are avoided. Particularly, in the first alternative embodiment, the HPU inverter means are already within the vehicle, specifically a traction inverter. A contactor is implemented between the traction inverter and the motor to switch the power source from the vehicle function (going to the motor) to the HPU function (operating as a generator and proceeding to the filter).
In another alternative embodiment, HEV components are again implemented as opposed to installing a separate HPU unit to avoid redundancy. In this second alternative embodiment, the DC-to-DC Converter is utilized as opposed to the Transformer. The inverter/rectifier means are then implemented after the DC-to-DC Converter to provide the appropriate current changes.